Autohelm Linear Drive Unit

[BlueSkyNick]

Ours (like the one in THIS Raymarine page ) is giving trouble, but I can't work out how to get it apart. If I do, what will I find inside?

The problems started when the tiller pin (SS pivot between linear drive and rudder arm) sheered with a strong tide up the chuff and on a broad reach too. At the same time, the wires got pulled out of the sensor. Now repaired both of these, but the motor in the drive unit is running continuously without doing anything.

I have had it depowered by removing the 12volt supply but this was some time after the above incident.

Might it be that something mechanical has worn/broken? There are two small black screws holding the cover on, but taking out still wont let me take the cover off.

WIll ask on Raymarine SUpport but hoped that somebody on here might be able to help.

 

[Richard10002]

Nick,

I had mine apart more times than I care to remember during my troubles last year.

I have an exploded diagram which I can send you if you let me have your email, (I know I should have it, but I cant find it).

IIRC, the cover is a tight fit and may need a bit of a tap wth a hammer to free it, (it's probably been untouched for over 10 years).

I got a lot of help on here from Hightech and gettingready, so you should be in good hands. a search for Autohelm or steering should find my posts and replies which would have been mainly between August and December 2006.

If the motor runs freely when trying to move the arm and turn the rudder, it suggests to me that the clutch isnt engaging to allow it to move the arm in and out. There is a 2nd 12v supply to the clutch and a connection may have come loose, so this is the first thing to look at.

On the computer at the right hand end there is power into the computer, then power out to the drive, (2 pairs of quite thick wires), then the 12v wires to the clutch.

When testing, I used a couple of separate 12v supplies near to where the drive is fitted so I could power up the clutch and the motor without any help. When you power the clutch without the drive running, you hear a slight click as it moves into position.

You'll see what you will find when you get my diagram - it's a bit daunting at first, but fairly straightforward and simple when you get to grips with it.

If you want any help, ask away - I should be internet connected for the foreseeable future, although I am leaving Riposto Marina tomorrow am. and heading to anchor at Taormina, (assuming the weather is OK), which as a couple of hours away.

Cheers

Richard

 

[BlueSkyNick]

YOUR Previous Thread found - very useful, thanks.

I foresee at least two more afternoons with head down under the bed !!

 

[Richard10002]

Nick,

There were a few threads on my steering problems as one solution seemed to lead quickly into another problem!!!

Hopefully it's just a power issue to the clutch... which could be a connection at the computer end, or a connection at the drive end.

However, whilst you are there it would be worth checking that the single gear wheel, (which I think is driven by the 4 orbital gears), is brass and not plastic.

My initial problem was caused because this plastic gear wore down.... the replacements are metal, so Raymarine obviously became aware of the problem and created a "Heavy gear Kit"!.

A further problem was caused because I put the 4 replacement orbital gears on upside down, which made the arm stick in one direction. Having resolved this, I then found that the cables had become so stiff, (coincidence), that the drive couldnt pull them to turn the wheel. Pouring 3 in 1 oild down the conduits resolved this in the short term, but 3 in 1 is too thin. Wurth HHS 2000pours easily then becomes sticky after a few minutes, and this has resolved the problem long term. I use a chopped off car aerial inserted into the pedestal and carefully placed at the top of the conduits, to pour the oil down the cables until I see it exiting at the other end.

I mention stiff cables as this was the cause of my blowing the FET's, (some kind of transistor), in the computer, which required me to send it away for new ones to be fitted. Apparently, the existing protection isnt good enough to save the FETs in certain load circumstances so, at the same time, I was advised to put a 15A fuse in the power supply to the computer, (the existing breaker is 40A). I've had the fuse fitted since lagos without problem... and we've had some heavy quarter seas for it to contend with.

If you can prevent the problems I have had by taking some action now, (if appropriate), life will be a bit easier steering wise <g>

Cheers

Richard

 

[Anonymous]

Nick, Before we left the UK I got Raymarine to check mine over and they didn't charge much. While it is nice to be able to DIY if I lived as close to them as you do, I'd get them to refurb it for me - pretty vital bit of kit. Regards, David

 

[rwoofer]

[ QUOTE ]
I foresee at least two more afternoons with head down under the bed !!

[/ QUOTE ]

Can't the whole unit be extracted for fixing? Can't imagine taking it apart in situ, unless yours is positioned differently to the one on Hana (basically underneath the bathing platform).

 

[BlueSkyNick]

well its under the bed closest to the transome, yes. The two afternoons mentioned are one to take it out and another one to put it back in again !!

If I am lucky, I might find something simple which can be fixed in visit, but expect to have to buy some new bits once I have got it apart.

Lemain - thanks for the tip about Raymarine. Now we are home, with the benefit of time and access, its mainly DIY stuff where possible (this is code for being skint!)

 

[rwoofer]

[ QUOTE ]
The two afternoons mentioned are one to take it out and another one to put it back in again !!

[/ QUOTE ]

Brings back memories /forums/images/graemlins/smile.gif

 

[Anonymous]

[ QUOTE ]
Lemain - thanks for the tip about Raymarine. Now we are home, with the benefit of time and access, its mainly DIY stuff where possible (this is code for being skint!)

[/ QUOTE ]You're welcome, hope you're enjoying Blighty? /forums/images/graemlins/wink.gif

I know how you feel about saving money and I'm the same but out of all the bits of kit I have on board, the autopilot is most important.

When I took mine off, it took me only a couple of minutes, I think. The connections were with plugs and sockets, a couple of nuts? or was it just a pin to remove? Very easy, anyway, then the whole assembly lifts off.

 

[Richard10002]

On the Moody 44 you have to be a contortionist with long arms, (Nick sould be OK there), and you have to be able to work without being able to see the job .. and this is just to get it off. Mine now has connectors on the wires. This enables me to power the motor and clutch with a separate 12v supply sitting on the bed base, aswell as aiding removal.

Nick - the only stuff you can do in situ is external wiring. Hopefully, this may be all you need to do! Anything else like opening it up needs it to be removed. Having thought about it, it's possible that the motor would spin if the small gear which started all my problems is worn - although I'm sure I got a grinding sound as the gears tried to grip but couldnt, rather than just a spinning motor sound.

If you need to take it out:

Remove the starboard side drawer and frame. Remove the 4 nut/bolts with a ratchet spanner in one hand with your arm through the top of the drawer space, and a normal, (or flexible head), spanner in the other hand with your arm in through the steering space. You will probably find you have your head on its' side with your cheek pressed against the top of the bed base .... your glasses will fall off if you wear them and, if you are not flexible in the arms/neck/chest area, you may pull some muscles getting out of this position - with hindsight, perhaps some stretching exercises would be a good idea before getting down to it - I dont think I'm joking!.

Once on the saloon table, remove the 2 screws holding the cover on - it's tightly engineered so needs a good wiggling, or even some tapping with a hammer, to release it.

You then find the long brass hexagonal things which the cover screws screwed into, and which screw into the body of the thing holding the back cover on - unscrew these. There are also 4 screws at the corners which also hold the back cover on - remove these, and the back cover comes off. You will see the magnetic clutch attached to the back cover, and the belt/gears arrangement which spin the rod which moves the balls, (which you cant see, and dont want to see), which spiral the arm in and out.

If I remember correctly, it's fairly straightforward in there but, if you want to remove the gears, there is a small circlip which is probably easy to deal with if you have the right circlip pliers. There is also a tight fitting pin through the spindle which I had to hammer out using a thin screwdriver and hammer. The gears and stuff then come apart easily, but you have to remember to put them all back together in the right orientation - it's critical that the 4 orbital gears have the ridge facing the right way - the exploded diagram tells you this, but watch which way they are when they come off and write it down, or photograph each step.. I wish I had photographed every step!

The above probably means nothing to you at the moment, but all will come clear if you need to get that far.

If you do get this far, and find that the very central gear is plastic/nylon or whatever, I would suggest replacing it. I had to buy a Heavy Gear Kit, (I've got the part number somewhere), which cost about £200 to get from a dealer in Lisbon to Bayona..... Hopefully less from Raymarine or a UK Chandlery??? It also includes a few other gears which are probably worth replacing while you have it out.

Mine used to struggle when working hard, and would often go into Standby... I'm guessing that this was the first signs of the plastic gear giving up the ghost... since replacing it with the new one, it's been as good as gold, even in big quarter seas.

Dont go further than this, i.e.

Hope this helps.... if you need the part number, let me know. I'm probably staying put in Taormina anchorage for a while, so internet shouldnt be a problem.

Richard

 

[Richard10002]

Nick

"Autopilot linear drive started making a grinding noise in Biscay. Took it off to find the centre splined gear completely worn, ( the gear is driven by, or drives, the 4 brass gears situated around it, and it is at the middle of a piece which is driven by the motor), and fitted Heavy Duty Gears service kit, (Raymarine part no N026)."

From:

http://www.ybw.com/forums/showflat.php/Cat/0/Number/1143748/page/0/fpart/1/vc/1

Richard

 

[Richard10002]

Nick - .......... Except that I have just had a look at the bill from Nautiradar in Lisbon, and the Linear Drive Heavy Duty Gears part number is N021..... NOT N026!!!

Found this which may help with the workings of Autohelm Autopilots - Service manual for ST4000

 

[BlueSkyNick]

thanks for all your help Richard - you paint a picture I had feared !!

From my initial inspection, I was planning to remove the wooden board on which the unit is mounted, via 4 bolts through to the battery compartment, rather than remove the unit from the wooden board as you have described.

I will report back next week, once I get away from the chiropractor !

 

[Richard10002]

Perhaps we have them fitted differently. Mine is bolted to a thick steel plate which is, in turn, bolted to the bit of the hull which separates the steering compartment from the battery/eberspacher compartment.... I guess there could be some wood involved... if so, it may be easier to remove the wooden board and take it from there.

Dont forget... you may only have to sort out some clutch wiring connections!

 

[Victorious]

Just a thought....
My type 2 Linear drive has a toothed drive belt...